Metal material for electrical electronic component

ABSTRACT

A metallic material for an electrical electronic includes a CU—Sun alloy layer ( 2 ) provided on a conductive base ( 1 ). A Cu concentration of the Cu—Sn alloy layer gradually decreases from the base side to the surface ( 3 ) side.

TECHNICAL FIELD

The present invention relates to a metallic material for an electricalelectronic component suitable for a sliding portion of a fitting-typemultipole connector and the like.

BACKGROUND ART

A plating material provided with a plating layer of tin (Sn), a tinalloy and others on a conductive base such as copper (Cu) and a copperalloy (referred to as a base hereinafter) is known to be ahigh-performance conductor having excellent conductivity and strength ofthe base and excellent electrical connectivity, corrosion resistance andsoldering quality of the plating layer. The plating material is widelyused for various terminals and connectors used in electric/electronicdevices. The plating material is normally undercoated with nickel (Ni),cobalt (Co), iron (Fe) and others having a barrier function on the baseto prevent an alloy component (referred to as a base componenthereinafter) such as zinc (Zn) from diffusing in the plating layer.

When the plating material is used as a terminal in a high-temperatureenvironment such as an inside of an engine room of a vehicle, forexample, although an oxide coating film is formed on a surface of the Snplating layer because the Sn plating layer on a surface of the terminalis oxidizable, the oxide coating film is brittle and breaks down whenthe terminal is connected and a non-oxidized Sn plating layer isexposed, thereby obtaining favorable electrical connectivity.

Because a fitting-type connector is multipolarized lately withadvancement of electronic control, a considerable force is necessary forplugging a male terminal group into/out of a female terminal group. Inparticular, plugging such a connector is difficult in a narrow spacesuch as the engine room of the vehicle, and it has been stronglydemanded to be able to reduce the force for plugging in/out such aconnector. Still more, as workability in connecting the connector isimproved by reducing the force for plugging in/out the connector, it hasbeen demanded to reduce the force for plugging in/out the connector alsofrom this point of view.

In order to reduce the plugging-in/out force, the Sn plating layer onthe surface of the connector terminal may be thinned to weaken contactpressure between the terminals. However, because the Sn plating layer issoft, a fretting phenomenon may occur between contact faces of theterminals, thereby causing inferior conduction between the terminals.

In the fretting phenomenon, the soft Sn plating layer on the surface ofthe terminal wears and is oxidized, becoming abrasion powder havinglarge specific resistance, due to fine vibration between the contactfaces of the terminals caused by vibration and changes in temperature.The lower the contact pressure between the terminals, the more thefretting phenomenon is prone to occur.

In order to assure a low plugging force, Japanese Patent ApplicationLaid-Open No. 2000-226645 Gazette, for example, has proposed a method offorming a hard Cu—Sn intermetallic compound layer that hardly causes thefretting phenomenon on the outermost surface by plating Sn on Cu or a Cualloy, implementing a reflow process and then treating by heat in anatmosphere at an oxygen concentration of 5% or less. However, the methodhas had a problem that workability of the plating process is inferior.Japanese Patent Application Laid-Open No. 2000-226645 Gazette has nodescription about a concentration of Cu—Sn in the Cu—Sn intermetalliccompound layer and has had a problem that it is difficult to perform thereflow heat-process in producing in line to adequately form an oxidecoating layer with a controlled thickness on the surface of the Cu—Snintermetallic compound layer.

Further, in order to assure the low plugging force and others, JapanesePatent Application Laid-Open No. 2004-68026 Gazette describes aconductive material for a connecting component that hardly causes thefretting phenomenon, in which a surface plating layer composed of a Nilayer and a Cu—Sn alloy layer is formed on a surface of a base composedof Cu or a Cu alloy in this order. However, the material is alsoinferior in terms of workability of plating process. Still more, it isdifficult to perform the reflow heat-process in producing in linebecause of the Cu—Sn alloy layer controlled by an average value of theconcentration of Cu—Sn.

Japanese Patent Application Laid-Open No. 2004-339555 Gazette describesforming a metal plate layer by plating metal on a surface of a metallicbase and forming a plated material mixed with soft regions spreadinglike a net and a hard region surround by the net of the soft region by areflow process. However, the plated material has a problem that the Cucomponent in the base diffuses to the plate uppermost surface and isoxidized, further increasing a contact resistance value.

Japanese Patent Application Laid-Open No. 2006-77307 Gazette describes aconductive material for a connecting component in which a Cu—Sn alloycoating layer composed of particles of several μm in diameter is formedalong irregularities of a surface of a base. Further, a Sn coating layeris melt and smoothed, and a part of the Cu—Sn alloy coating layer isexposed on the surface of the material.

When there is no Cu layer in a substrate and a Ni substrate exists,there would be no problem. However, when the Cu layer exists or no Nisubstrate exists, even if there would be no problem in an initial state,under an environment in which a connecting component is mounted in anactual car and sliding and thermal loads are applied at the same time,the pure Sn portion is scraped due to sliding and Cu diffuses up to asurface and oxidized, thereby increasing resistance.

DISCLOSURE OF THE INVENTION

According to the invention, the following aspects are provided:

-   (1) A metallic material for an electrical electronic component    comprising a Cu—Sn alloy layer provided on a conductive base,    wherein the Cu—Sn alloy layer has a Cu concentration gradually    decreasing from a side of the conductive base toward a surface side    thereof;-   (2) A metallic material for an electrical electronic component    comprising a Cu—Sn alloy layer provided on a conductive base,    wherein the Cu—Sn alloy layer has a Cu concentration gradually    decreasing from a side of the conductive base toward a surface side    thereof, and said Cu—Sn alloy layer contains Sn or a Sn alloy    dispersed partially;-   (3) A metallic material for an electrical electronic component    comprising one layer formed of one of Ni, Co and Fe or an alloy    thereof provided on a conductive base and a Cu—Sn alloy layer    provided on the one layer, wherein the Cu—Sn alloy layer has a Cu    concentration gradually decreasing from a side of the conductive    base toward a surface side thereof;-   (4) A metallic material for an electrical electronic component    comprising one layer formed of one of Ni, Co and Fe or an alloy    thereof provided on a conductive base and a Cu—Sn alloy layer    provided on the one layer, wherein the Cu—Sn alloy layer has a Cu    concentration gradually decreasing from a side of the conductive    base toward a surface side thereof, and said Cu—Sn alloy layer    contains Sn or a Sn alloy dispersed partially;-   (5) A metallic material for an electrical electronic component two    layers formed of one of Ni, Co and Fe or an alloy thereof provided    on a conductive base and a Cu—Sn alloy layer provided on the two    layers, wherein the Cu—Sn alloy layer has a Cu concentration    gradually decreasing from a side of the conductive base toward a    surface side thereof;-   (6) A metallic material for an electrical electronic component    comprising two layers formed of one of Ni, Co and Fe or an alloy    thereof provided on a conductive base and a Cu—Sn alloy layer    provided on the two layers, wherein the Cu—Sn alloy layer has a Cu    concentration gradually decreasing from a side of the conductive    base toward a surface side thereof, and said Cu—Sn alloy layer    contains Sn or a Sn alloy dispersed partially;-   (7) The metallic material for an electrical electronic component    according to one of (1), (3) and (5), wherein the Cu—Sn alloy layer    includes a half portion on the side of the conductive base having    the Cu concentration of 50 to 100 mol % and the Sn concentration of    0 to 50 mol %, and a half portion on the surface side having the Cu    concentration of 40 to 95 mol % and the Sn concentration of 5 to 60    mol %;-   (8) The metallic material for an electrical electronic component    according to one of (2), (4) and (6), wherein said Cu—Sn alloy layer    includes a half portion on the side of the conductive base having    the Cu concentration of 50 to 100 mol % and the Sn concentration of    0 to 50 mol %, and a half portion on the surface side having the Cu    concentration of 0 to 95 mol % and the Sn concentration of 5 to 100    mol %;-   (9) The metallic material for an electrical electronic component    according to one of (1) through (8), wherein said Cu—Sn alloy layer    has a thickness of 0.1 to 3.0 μm;-   (10) A method for manufacturing the metallic material for an    electrical electronic component according to one of (1) through (9),    comprising the steps of: laminating sequentially Cu and Sn on the    conductive base or one of Ni, Co and Fe or the alloy thereof to form    a laminate; applying a heat treatment on the laminate; and applying    a cooling process on the laminate applied with the heat treatment;-   (11) The method for manufacturing the metallic material for an    electrical electronic component according to (10), wherein, in the    step of applying the heat treatment, the laminate passes through a    reflow furnace at an in-furnace temperature of higher than 300° C.    and lower than 900° C. for three to 20 seconds;-   (12) The method for manufacturing the metallic material for an    electrical electronic component according to (10), wherein, in the    step of applying the cooling treatment, the laminate passes through    a liquid at a temperature between 20° C. and 80° C. for one to 100    seconds; and-   (13) The method for manufacturing the metallic material for an    electrical electronic component according to (10), wherein, in the    step of applying the cooling treatment, the laminate passes through    air at a temperature between 20° C. and 60° C. for one to 300    seconds, and then through a liquid at a temperature between 20° C.    and 80° C. for one to 100 seconds.

The abovementioned and other features and advantages of the inventionwill be more apparent from the following description understood byappropriately making reference to the appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal section view showing one mode of a metallicmaterial for electrical electronic component the invention.

FIG. 2 is a longitudinal section view showing one mode of the metallicmaterial for electrical electronic component the invention.

FIG. 3 is a longitudinal section view showing one mode of the metallicmaterial for electrical electronic component the invention.

FIG. 4 is a longitudinal section view showing one mode of the metallicmaterial for electrical electronic component the invention.

FIG. 5 is a longitudinal section view showing one mode of the metallicmaterial for electrical electronic component the invention.

FIG. 6 is a longitudinal section view showing one mode of the metallicmaterial for electrical electronic component the invention.

FIG. 7 is a longitudinal section view showing one mode of the metallicmaterial for electrical electronic component the invention.

FIG. 8 is a longitudinal section view showing one mode of the metallicmaterial for electrical electronic component the invention.

FIG. 9 is a microscope photograph, taken by a SEM, of the metallicmaterial for electrical electronic component of a first embodiment.

FIG. 10 is a Cu—Sn—Ni map of the first embodiment.

FIG. 11 is a microscope photograph, taken by the SEM, of the metallicmaterial for electrical electronic component of a second embodiment.

FIG. 12 is a Cu—Sn—Ni map of the second embodiment.

FIG. 13 is a perspective explanatory diagram of a fine vibration testingmethod of a test example 1.

FIG. 14 is an explanatory diagram diagrammatically showing layeredstructures to explain sections of sample materials of third and fourthembodiments.

BEST MODES FOR CARRYING OUT THE INVENTION

According to the present invention, a metallic material for anelectrical electronic component is provided with a Cu—Sn alloy layer ona conductive base or on an undercoat formed on the conductive base andCu concentration in the Cu—Sn alloy layer gradually decreases from theside of the base toward the side of a surface of the metal material. Themetallic material for electrical electronic component is formed byforming the Cu—Sn alloy layer by plating Sn on a plating layer formed onthe conductive base and by implementing a heat treatment and bydecreasing the Cu concentration gradually from the base side to thesurface side.

The phrase “the Cu concentration of the Cu—Sn alloy layer graduallydecreases from the base side to the surface” means that the Cuconcentration measured at least three places whose depth from thesurface of the layer is different in section of the Cu—Sn alloy layer islow in order closer to the surface.

While the Cu concentration of the Cu—Sn alloy layer of the inventiongradually decreases from the base side to the surface, the Cuconcentration in a half of the base side of the thickness is preferableto be 50 to 100 mol % and is more preferable to be 65 to 100 mol % andthe Sn concentration is preferable to be 0 to 50 mol % of the remainingpart and more preferable to be 0 to 35 mol % (this is concentration inwhich inevitable impurities other than Cu and Sn are neglected. The sameapplies hereinafter).

In a case when Sn or the Sn alloy is not distributed partially, the Cuconcentration on a half on the surface side is preferable to be 40 to 95mol % and more preferable to be 65 to 85 mol %. The Sn concentration ispreferable to be 5 to 60 mol % and more preferable to be 15 to 35 mol %.

In a case when Sn or the Sn alloy is dispersed partially, the Cuconcentration in the half of the surface side is preferable to be 0 to95 mol % and more preferable to be 65 to 85 mol %. The Sn concentrationis preferable to be 5 to 100 mol % and more preferable to be 15 to 35mol %.

If the Cu concentration in the half of the base side is too low (the Snconcentration is too high), a pure Sn layer tends to be formed on theoutermost surface and fretting resistance deteriorates.

If the Sn concentration in the half of the surface side is too low, theheat resistance decreases, leading to the quick increase of resistancewhen used under a high-temperature environment.

The metallic material for electrical electronic component of theinvention has a room for permitting Cu to diffuse with Sn even if a Culayer exists in a substrate or no Ni substrate exists because the Cu—Snalloy layer is what is formed so that the Cu concentration within theCu—Sn alloy layer on the upper side in gradation, i.e., the Snconcentration is low in the Cu—Sn alloy layer on the surface side. As aresult, it becomes possible to retard Cu from being exposed on theoutermost surface and being oxidized even if the metallic material forelectrical electronic component receives thermal load.

A thickness of the Cu—Sn alloy layer is preferably in a range from 0.1to 3.0 μm and more preferable to be 0.3 to 1.5 μm. If this thickness istoo thick, Kirkendall voids tend to be generated in a diffusion process,possibly causing delamination of plating. Still more, it is presumedthat costs for plating increase due to the increase of heat-treatmenttemperature and time. If the thickness is too thick, the contactresistance may increase, the heat resistance may be deteriorated and thefretting resistance may be deteriorated.

In the present invention, copper and copper alloys such as phosphorbronze, brass, alpaca, beryllium copper and Corson alloy, iron and ironalloys such as stainless steel, compound materials such as copper-coatedsteel material and nickel-coated steel material, various nickel alloyand aluminum alloys having conductivity, mechanical strength and heatresistance required for terminals may be used for the conductive base.

Among the metals and alloys (material) described above, the coppermaterials such as copper and the copper alloys are suitable inparticular because they excel in the balance of the conductivity andmechanical strength. If the conductive base is made of materials otherthan the copper material, it is preferable to coat copper or the copperalloy on the surface of the conductive base.

While the Sn plating may be formed by nonelectrolytic plating, it isdesirable to form by electroplating. A thickness of the Sn layer formedby the Sn plating is preferable to be in a range from 0.01 to 5.0 μm. Snelectroplating of the uppermost layer may be carried out underconditions of 30° C. or less of plating temperature and 5 A/cm² ofcurrent density by employing tin sulfate bath for example. However,these conditions are not limited to these and may be appropriately set.

According to the invention, the laminate material whose uppermost layeris Sn-plated is treated by heat. Conditions for this heat treatment areselected so as to form the Cu—Sn alloy layer in which the Cuconcentration gradually decreases from the base side to the surfaceside. When the heat treatment is implemented by a reflow process(continuous process), it is preferable to heat in an in-furnacetemperature range of 300° C. or more to under 900° C. for three to 20seconds (or preferably from 5 to 10 seconds or more preferably from 6 to8 seconds).

These temperature and time are adopted to obtain the Cu—Sn alloy layerwhose Cu concentration gradually decreases from the base side to thesurface side.

It is noted that it is preferable to hold the material described abovefor 0.1 to 200 hours within a furnace whose temperature is 60 to 200° C.when the heat treatment is carried out in a way of batch process.

Still more, it is preferable to pass the laminate material treated byheat by the reflow process into liquid within a cooling tank by taking 1to 100 seconds (or more preferably 3 to 10 seconds) to quench thematerial. Temperature of the liquid is preferable to be in a range from20 to 80° C. (or more preferably 30 to 50° C.). It is also preferable topass the laminate material treated by heat into gas of a cold-air unitwithin the in-furnace atmosphere of 20 to 60° C. by taking 1 to 300seconds to gradually cool the material.

It becomes possible to obtain the plating structure in which the Cuconcentration within the Cu—Sn alloy layer is gradational and todisperse pure Sn within the Cu—Sn alloy layer by forcibly ending thediffusion of Cu and Sn in mid-stream or by rapidly reducing theirdiffusion speed by such cooling process.

FIG. 1 is a schematic section view showing a metallic material forelectrical electronic component of one embodiment of the invention. Themetallic material for electrical electronic component of the mode shownin FIG. 1 is obtained by plating Sn on the conductive base 1, bytreating by heat and by provided the Cu—Sn alloy layer 2 whose Cuconcentration is gradually reduced from the side of the base 1 to theside of the surface (material surface) 3 for example. In this mode, thecopper material or a Cu base material coated with copper or a copperalloy is used as the conductive base 1. By treating by heat as describedabove, Cu components of the Cu base material coated with copper or thecopper alloy on the surface of the conductive base 1 thermally diffuseinto the Sn plating layer and Sn also diffuses into the base 1 by theheat treatment in this mode. Due to that, the Cu—Sn alloy layer 2 whoseCu concentration is gradually reduced from the base side 1 to thesurface 3 is formed. No clear boundary between the conductive base 1 andthe Cu—Sn alloy layer 2 in section is also formed.

FIG. 2 is a schematic section view showing a metallic material forelectrical electronic component of another one embodiment of theinvention. The metallic material for electrical electronic component ofthe mode shown in FIG. 2 is obtained by coating the conductive base 1with Sn plating or the like, by treating by heat to provide the Cu—Snalloy layer 2 whose Cu concentration is gradually reduced from the sideof the base 1 to the side of the surface 3 and Sn (4) is partiallydispersed within the Cu—Sn alloy layer 2. The material of the conductivebase 1 and the boundary between the conductive base 1 and the Cu—Snalloy layer 2 are the same with the mode shown in FIG. 1. The Sn (4) maybe metallic Sn or a Sn alloy (containing Sn by more than 50 mass %).While any method may be used for dispersing the Sn (4), the metallic Snor the Sn alloy is dispersed by optimizing conditions of the heattreatment such as the reflow process and the batch process so that thecoated Sn is not totally alloyed with the base 1 or with Cu existing onthe surface thereof (specifically, the heat treatment is finished beforethe coated Sn is totally alloyed with the base 1 or Cu existing on thesurface thereof).

The dispersion state is preferable if at least part of the metallic Snand the Sn alloy (Sn concentration is more than 80 mol %) is exposed onthe surface of the uppermost layer and Sn or the Sn alloy is dispersedlike an island or a dot when seen planarly. Still more, an oxide filmfrom 0 to 100 nm may be formed on the outermost layer.

A still other embodiment of the invention is the metallic material forelectrical electronic component in which the conductive base 1 coatedwith any one type of metal among Ni, Co and Fe or with an alloycontaining those metals as a main component (more than 50 mass %) byplating and is then treated by heat to provide the Cu—Sn alloy layer 2whose Cu concentration is gradually reduced from the base side 1 towardthe surface 3.

FIG. 3 is a schematic section view showing a metallic material forelectrical electronic component of the present embodiment in which theconductive base 1 is coated with Cu by plating or the like. In themetallic material for electrical electronic component of the mode shownin FIG. 3, the conductive base 1 is provided with a Cu layer 5 and theCu layer 5 is coated with Sn by plating or the like. Then, a heattreatment is implemented so that Cu components thermally diffuse fromthe Cu layer 5 into the Sn layer and Sn also diffuses into the Cu layer5. Therefore, the Cu—Sn alloy layer 2 whose Cu concentration isgradually reduced from the side of the base 1 to the side of the surface3 is formed. No clear boundary between the Cu layer 5 and the Cu—Snalloy layer 2 in section is also formed.

FIG. 4 is a schematic section view showing a metallic material forelectrical electronic component of the present embodiment in which theconductive base 1 is plated with Ni. In the metallic material forelectrical electronic component of the mode shown in FIG. 4, theconductive base 1 is coated with a Ni layer (undercoat) 6 by plating orthe like and the Ni layer 6 is coated further with a Cu layer and a Snlayer in this order by plating or the like. Here, the heat treatment isimplemented, so that the Cu layer provided on the Ni layer 6 and the Snplating layer provided thereon mutually diffuse and the Cu—Sn alloylayer 2 whose Cu concentration is gradually reduced from the base sideto the surface side is formed. The similar metallic material forelectrical electronic component may be obtained also when Co plating orFe plating is implemented instead of the Ni plating.

A still different embodiment of the invention is the metallic materialfor electrical electronic component in which the conductive base 1coated with any one type of metal among Ni, Co and Fe or with an alloycontaining those metals as a main component (more than 50 mass %) byplating or the like, is coated with Cu and Sn in this order and is thentreated by heat to provide the Cu—Sn alloy layer 2 whose Cuconcentration is gradually reduced from the base side 1 toward thesurface 3 and Sn or the Sn alloy is partially dispersed within the Cu—Snalloy layer 2.

FIG. 5 is a schematic section view showing a metallic material forelectrical electronic component of the present embodiment in which theconductive base 1 is coated with Cu by plating or the like. In themetallic material for electrical electronic component of the mode shownin FIG. 5, the conductive base 1 is provided with the Cu layer 5 and theCu layer 5 is coated with Sn by plating or the like. Then, a heattreatment is implemented, so that Cu components thermally diffuse fromthe Cu layer 5 into the Sn layer and Sn also diffuses into the Cu layer5. Therefore, the Cu—Sn alloy layer 2 whose Cu concentration isgradually reduced from the side of the base 1 to the side of the surface3 is formed. No clear boundary between the Cu layer 5 and the Cu—Snalloy layer 2 in section is formed. The Sn (4) is partially dispersedwithin the Cu—Sn alloy layer 2. The method for dispersing the Sn (4) isthe same with the dispersing method in the mode show in FIG. 2 describedabove.

FIG. 6 is a schematic section view showing a metallic material forelectrical electronic component of the present embodiment in which theconductive base 1 is plated with Ni. In the metallic material forelectrical electronic component of the mode shown in FIG. 6, theconductive base 1 is coated with a Ni layer 6 by plating or the like andthe Ni layer 6 is coated further with a Cu layer and a Sn layer in thisorder by plating or the like. Here, the heat treatment is implemented,so that the Cu layer provided on the Ni layer 6 and the Sn plating layerprovided thereon mutually diffuse and the Cu—Sn alloy layer 2 whose Cuconcentration is gradually reduced from the base side to the surfaceside is formed. The Sn (4) is partially dispersed within the Cu—Sn alloylayer 2. The method for dispersing the Sn (4) is the same with thedispersing method in the mode shown in FIG. 2 described above.

A still different embodiment of the invention is a metallic material forelectrical electronic component in which the conductive base 1 coatedwith any one type of metal among Ni, Co and Fe or with an alloycontaining those metals as a main component (more than 50 mass %) by twolayers by plating or the like, is coated with Cu and Sn in this orderand is then treated by heat to provide the Cu—Sn alloy layer 2 whose Cuconcentration is gradually reduced from the base side 1 toward thesurface 3. A combination of two types of plating implemented on theconductive base 1 is not specifically limited.

FIG. 7 is a schematic section view showing a metallic material forelectrical electronic component of the present embodiment in which theconductive base 1 is coated with Ni as an under layer and with Cu as anupper layer by plating or the like. In the metallic material forelectrical electronic component of the mode shown in FIG. 7, theconductive base 1 is coated with a Ni layer 6 and a Cu layer 5 in thisorder and the Cu layer 5 is coated further with a Sn layer by plating orthe like. Here, the heat treatment is implemented, so that the Cucomponents thermally diffuse from the Cu layer 5 to the Sn layer and Snalso diffuses into the Cu layer 5 by the heat treatment described above.Due to that, the Cu—Sn alloy layer 2 whose Cu concentration is graduallyreduced from the base side to the surface side is formed. No clearboundary between the Cu layer 5 and the Cu—Sn alloy layer 2 in sectionis formed.

A still other embodiment of the invention is a metallic material forelectrical electronic component in which the conductive base 1 coatedwith any one type of metal among Ni, Co and Fe or with an alloycontaining those metals as a main component (more than 50 mass %) by twolayers by plating or the like, is coated with Cu and Sn in this order byplating or the like and is then treated by heat to provide the Cu—Snalloy layer 2 whose Cu concentration is gradually reduced from the baseside 1 toward the surface 3 and Sn or the Sn alloy is partiallydispersed within the Cu—Sn alloy layer 2. A combination of two types ofplating implemented on the conductive base 1 is not specificallylimited.

FIG. 8 is a schematic section view showing a metallic material forelectrical electronic component of the present embodiment in which theconductive base 1 is coated with Ni as an under layer and with Cu as anupper layer by plating or the like. In the metallic material forelectrical electronic component of the mode shown in FIG. 8, theconductive base 1 is coated with a Ni layer 6 and a Cu layer 5 in thisorder and the Cu layer 5 is coated further with a Sn layer by plating orthe like. Here, the heat treatment is implemented, so that the Cucomponents thermally diffuse from the Cu layer 5 into the Sn layer andSn also diffuses into the Cu layer 5 by the heat treatment describedabove. Due to that, the Cu—Sn alloy layer 2 whose Cu concentration isgradually reduced from the base side to the surface side is formed. Noclear boundary between the Cu layer 5 and the Cu—Sn alloy layer 2 insection is formed. Sn (4) or the Sn alloy is partially dispersed withinthe Cu—Sn alloy layer 2. The method for dispersing the Sn (4) is thesame with the dispersing method in the mode shown in FIG. 2 describedabove.

The Cu—Sn alloy layer in the outermost layer contains a Cu—Snintermetallic compound layer in the present invention. The Cu—Snintermetallic compound in the invention includes Cu₆Sn₅, Cu₃Sn andothers. The invention includes those in which those intermetalliccompounds are mixed.

In the present invention, preferably the conductive base 1 is providedwith the undercoat such as the Ni layer 6 as described in the modesshown in FIGS. 4, 6, 7 and 8. It becomes possible to prevent thecomponents of the base 1 from diffusing into the outermost layer byproviding the undercoat. As the undercoat provided on the conductivebase 1, metals such as Ni, Co and Fe having a barrier function forpreventing the component of the base from thermally diffusing into theoutermost layer and Ni—P, Ni—Sn, Co—P, Ni—Co, Ni—Co—P, Ni—Cu, Ni—Cr,Ni—Zn, Ni—Fe and other alloys may be suitably used. These metals andalloys have favorable plating treatability and have no problem in termsof their cost. Among them, Ni and Ni alloy are recommended because theirbarrier function does not deteriorate even under a high-temperatureenvironment.

While a fusion point of the metal (alloy) such as Ni used for theundercoat described above is as high as 1000° C., temperature of useenvironment of the connector is lower than 200° C., so that theundercoat itself hardly causes thermal diffusion and its barrierfunction is effectively exhibited. The undercoat also has a function ofenhancing adhesion between the conductive base and an intermediate layerdescribed later depending on a material of the conductive base. Thebarrier function of the undercoat is not fully exhibited if itsthickness is under 0.01 μm and plating distortion thereof becomes largeand the undercoat is prone to fall away if the thickness exceeds 3 μm.Accordingly, the thickness of the undercoat is preferable to be in arange from 0.01 to 3 μm. Considering a terminal workability, an upperlimit of the thickness of the undercoat is preferable to be 1.5 μm ormore preferable to be 0.5 μm.

The metallic material for electrical electronic component of the presentinvention is what the conductive base 1 is provided with theintermediate layer composed of the Cu layer 5 on the undercoat made ofNi or the like as described in the mode shown in FIGS. 7 and 8. Itbecomes possible to prevent the component of the undercoat such as Nifrom diffusing into the outermost layer, to stably obtain favorableelectrical connectivity and to readily form the Cu—Sn alloy layer whoseCu concentration is gradually reduced from the base side to the surfaceby providing the intermediate layer. A thickness of the intermediatelayer is preferable to be 0.01 to 3 um or more preferable to be 0.1 to0.5 μm.

The metallic material for electrical electronic component of theinvention may be formed into any shape such as a strip, round wire andrectangular wire. The metallic material for electrical electroniccomponent of the invention may be worked into an electric/electronicpart such as a fitting-type multipole connector for use in automobilesby a normal method. For instance, a connector created by using themetallic material for electrical electronic component of the inventionmay be what weakens a contact pressure between terminals, causes nofretting phenomenon between contact faces of terminals and suppresses anoccurrence of inferior conductivity between the terminals.

The metallic material for electrical electronic component of theinvention may be manufactured readily by a reflow thermal treatment andmay improve heat resistance of a plating material. It is because theabundant Cu on the base side reacts with the abundant Sn on the surfaceside within the Cu—Sn alloy layer even under a high-temperatureenvironment when this material is used as an electric/electronicmaterial. Still more, the electric/electronic material manufactured byusing the metallic material for electrical electronic component of theinvention can remarkably suppress a sharp rise of resistance (fretting)at an electrical contact during sliding.

Still more, the metallic material for electrical electronic component inwhich the conductive base is provided with the undercoat made of Ni orthe like can prevent the components of the base from diffusing into theoutermost layer. Still more, the material in which the intermediatelayer made of Cu or the like is provided on the undercoat can preventthe component such as Ni of the base from diffusing into the outermostlayer. Accordingly, it becomes possible to stably obtain favorableelectrical connectivity.

Further, the material in which Sn or the Sn alloy is partially dispersedwithin the Cu—Sn alloy layer has the effect that no CuO and the like isformed by exposed Cu and the contact resistance is stabilized becausethere is such a room that a Cu—Sn alloy is formed as Cu existing underthe Cu—Sn alloy layer reacts with Sn or the Sn alloy dispersed withinthe Cu—Sn alloy layer.

Embodiments

While exemplary embodiments of the invention will be explained below indetail, the invention is not limited to them.

First Exemplary Embodiment

A plated laminate was fabricated by degreasing and pickling a copperstrip of 0.25 mm thick in this order and by electroplating the copperalloy strip by laminating Ni, Cu and Sn in this order. Plating of eachmetal was implemented under the following conditions:

(a) Ni Plating

Plating Bath Composition

Component: Concentration: Nickel sulfamate 500 g/l Boric acid 30 g/lBath Temperature: 60° C. Electrical Density: 5 A/dm² Thickness ofPlating: 0.5 μm

(b) Cu Plating

Plating Bath Composition

Component: Concentration: Copper sulfate 180 g/l Sulfuric acid 80 g/lBath Temperature: 40 Electrical Density: 5 A/dm² Thickness of Plating:0.8 μm

(c) Sn Plating

Plating Bath Composition

Component: Concentration: Stannous sulfate 80 g/l sulfuric acid 80 g/lBath Temperature: 30° C. Electrical Density: 5 A/dm² Thickness ofPlating: 0.3 μmIt is noted that the thickness described above may be appropriatelymodified by plating time.

Next, this plated laminate was treated by a reflow process within areflow furnace at 740° C. for 7 seconds to obtain the metallic material.FIG. 9 shows a photograph (horizontal width: 11.7 μm) of this materialtaken by SEM (Scanning Electron Microscope) and FIG. 10 shows anelectronic image (Cu—Sn—Ni map) taken by AES (Auger ElectronSpectroscopy) of a measured section containing the surface shown in theSEM photograph. This measurement was carried out by preparing a samplefor AES analysis with a sample angle of 60 degrees and an obliquesection of 30 degrees by FIB (Focused Ion Beam) at first, by analyzingthe sample by inclining so that the oblique section of 30 degrees of theAES analysis becomes horizontal and by measuring the thickness of eachlayer by obtaining AES images. Table 1 shows Sn and Cu concentrations(mol %) in the respective measuring surface 1 (11), 2(12) and 3 (13)shown in FIG. 9 found by AES qualitative analysis:

TABLE 1 [mol %] MEASURING SURFACE Sn Cu 1 26.8 73.2 2 18.2 81.8 3 — 100

As shown in Table 1 and FIG. 10, the material of the present embodimentis formed such that the Cu layer 5 and the Cu—Sn alloy layer 2 areformed on the Ni layer 6 substantially continuously and the Cuconcentration is gradually reduced from the base side toward thesurface.

Second Exemplary Embodiment

A plated laminate was fabricated by degreasing and pickling a copperstrip of 0.25 mm thick in this order and by electroplating the copperalloy strip by laminating Ni, Cu and Sn in this order. Plating of eachmetal was implemented under the following conditions:

(a) Ni Plating

Plating Bath Composition

Component: Concentration: Nickel sulfamate 500 g/l Boric acid 30 g/lBath Temperature: 60° C. Electrical Density: 5 A/dm² Thickness ofPlating: 0.5 μm

(b) Cu Plating

Plating Bath Composition

Component: Concentration: Copper sulfate 180 g/l Sulfuric acid 80 g/lBath Temperature: 40° C. Electrical Density: 5 A/dm² Thickness ofPlating: 0.8 μm

(c) Sn Plating

Plating Bath Composition

Component: Concentration: Stannous sulfate 80 g/l sulfuric acid 80 g/lBath Temperature: 30° C. Electrical Density: 5 A/dm² Thickness ofPlating: 0.5 μmIt is noted that the thickness described above may be appropriatelymodified by plating time.

Next, this plated laminate was heat-treated by a reflow process within areflow furnace at 740° C. for 7 seconds to obtain the metallic material.FIG. 11 shows a photograph (horizontal width: 11.7 μm) of this materialtaken by SEM and FIG. 12 shows an electronic image (Cu—Sn—Ni map) takenby AES of a measured section containing the surface shown in the SEMphotograph in FIG. 11. Table 2 shows Sn and Cu concentrations (mol %) inthe respective measuring surface 1 (21), 2(22) and 3 (23) shown in FIG.11 found by AES qualitative analysis:

TABLE 2 [mol %] MEASURING SURFACE Sn Cu 1 84.3 15.7 2 38.8 61.2 3 — 100

As shown in Table 2 and FIG. 12, the material of the present embodimentis formed such that the Ni layer 6, the Cu layer 5 and the Cu—Sn alloylayer 2 are formed on the base 1 in this order, the boundary between theCu layer 5 and the Cu—Sn alloy layer 2 is not clear and the Cuconcentration is gradually reduced from the base side toward thesurface. Still more, the Sn (4) is dispersed like an island within theCu—Sn alloy layer 2.

First Exemplary Test

The following fine sliding test was carried out on the respectivemetallic materials for electrical electronic component obtained in thefirst and second exemplary embodiments by sliding and reciprocating thematerial up to 1,000 times to measure changes of values of contactresistance continuously.

The fine sliding test was carried out by preparing two each pieces oftesting metallic materials 31 and 32, by providing a semi-sphericalbulge section (convex outer surface is the outermost layer surface) 31 ahaving a radius of curvature of 1.8 mm in the testing metallic materialpiece 31, by contacting an outermost layer surface 32 a of the testingmetallic material piece 32 after degreasing and washing, respectively,to the semi-spherical bulge section 31 a with contact pressure 3 N, byreciprocating and sliding the both in this state with 30 μm of a slidingdistance under an environment of 20° C. of temperature and 65% ofhumidity, by flowing 5 mA of constant current while loading 20 mV ofopen voltage between the both testing metallic material pieces 31 and 32and by finding the changes of electric resistance per one second bymeasuring a voltage drop during sliding by a four-terminal method. It isnoted that frequency of the reciprocal movement was about 3.3 Hz. Thevalue of contact resistance before the fine sliding test was 0.1 mΩ whenthe testing metallic material pieces 31 and 32 are used as the materialsof the first embodiment and was 0.5 mΩ when used as the materials of thesecond embodiment. Further, the maximum contact resistance value duringthe fine sliding test was 4.0 mΩ when the testing metallic materialpieces 31 and 32 are used as the materials of the first embodiment andwas 4.1 mΩ when used as the materials of the second embodiment. Thus, nofretting occurred in the materials of the present embodiment.

Third Exemplary Embodiment

A plated laminate was fabricated by plating a copper alloy strip bylaminating Ni, Cu and Sn in the same manner with the firs embodiment andthe same heat treatment was implemented to obtain each metallicmaterial. However, thicknesses of plating of Cu and Sn are those in theCu—Sn layer in the following Table 3 and no Ni plating is implemented inthe case when there is no undercoat Ni layer.Each metallic material thus obtained was tested as a specimen piece andTable 3 shows their plating modes and evaluation results:

TABLE 3 PLATING MODE Cu—Sn LAYER WHETHER WHETHER THICKNESS POINTANALYSIS OF PURE PURE Sn OF PURE Sn WHETHER THICK- Cu CONCENTRATION SnLAYER PART EXISTS PART UNDER- NESS OF WHETHER PURE Sn AVERAGE EXISTS ORNOT WITHIN COAT Ni WHOLE EXISTS OR NOT OF (1) + (2) AVERAGE OR NOTWITHIN UPPER- LAYER MODE OF Cu-Sn ON SURFACE OF (SURFACE OF (3) + (4)WITHIN UPPERMOST MOST EXISTS Cu—Sn LAYER CONCENTRATION SIDE) (BASE SIDE)UPPERMOST SURFACE SURFACE OR TEST NO. LAYER [μm] ANALYSIS LINE [mol %][mol %] SURFACE [mol %] [μm] NOT BASE 1 WHOLE 0.6 NOT EXIST 75.9 81.2NOT EXIST NOT EXIST 0 EXISTS COPPER SURFACE ALLOY OF Cu—Sn 2 WHOLE 0.4NOT EXIST 74.9 80.2 NOT EXIST NOT EXIST 0 EXISTS COPPER SURFACE ALLOY OFCu—Sn 3 WHOLE 0.8 NOT EXIST 56.9 66.9 NOT EXIST NOT EXIST 0 NOT COPPERSURFACE EXIST ALLOY OF Cu—Sn 4 WHOLE 2.4 NOT EXIST 84.3 90.5 NOT EXIST —— EXISTS COPPER SURFACE ALLOY OF Cu—Sn 5 WHOLE 0.2 NOT EXIST 68.1 73.7NOT EXIST NOT EXIST 0 NOT COPPER SURFACE EXIST ALLOY OF Cu—Sn 6 WHOLE0.6 NOT EXIST 37.8 53.3 NOT EXIST NOT EXIST 0 EXISTS COPPER SURFACEALLOY OF Cu—Sn 7 WHOLE 0.6 NOT EXIST 42.6 48.1 NOT EXIST NOT EXIST 0EXISTS COPPER SURFACE ALLOY OF Cu—Sn 8 WHOLE 0.6 NOT EXIST 32.3 44 NOTEXIST NOT EXIST 0 EXISTS COPPER SURFACE ALLOY OF Cu—Sn 9 WHOLE 3.5 NOTEXIST 86.2 93.6 NOT EXIST NOT EXIST 0 EXISTS COPPER SURFACE ALLOY OFCu—Sn 10 WHOLE 0.05 NOT EXIST 77.7 81.9 NOT EXIST NOT EXIST 0 NOT COPPERSURFACE EXIST ALLOY OF Cu—Sn 11 PARTIAL 1.1 NOT EXIST 66.9 84.2 NOTEXIST — — EXISTS COPPER Cu—Sn EXISTS 68.3 85.4 EXISTS 91.9 0.2 ALLOY 12PARTIAL 1.3 NOT EXIST 69.1 86.7 NOT EXIST — — EXISTS COPPER Cu—Sn EXISTS70.2 87.2 EXISTS 88.5 0.2 ALLOY 13 PARTIAL 1.6 NOT EXIST 51.9 69.7 NOTEXIST — — NOT COPPER Cu—Sn EXISTS 48.4 72.8 EXISTS 95.1 0.3 EXIST ALLOY14 PARTIAL 0.4 NOT EXIST 65.6 85.5 NOT EXIST — 0.1 NOT COPPER Cu—SnEXISTS 68.8 86.7 90.5 EXIST ALLOY 15 PARTIAL 2.5 NOT EXIST 56.6 85.5 NOTEXIST — 0.4 NOT COPPER Cu—Sn EXISTS 59.3 87.5 EXISTS 97.2 EXIST ALLOY 16PARTIAL 1.1 NOT EXIST 45.1 62.4 EXISTS — 0.2 EXISTS COPPER Cu—Sn EXISTS42.3 62.1 EXISTS 88.5 ALLOY 17 PARTIAL 3.5 NOT EXIST 71.3 96 NOT EXIST —0.8 EXISTS COPPER Cu—Sn EXISTS 69.7 96.7 EXISTS 95.2 ALLOY 18 PARTIAL0.08 NOT EXIST 71.1 86.2 NOT EXIST — 0.03 NOT COPPER Cu—Sn EXISTS 75.587.1 EXISTS 89.7 EXIST ALLOY 19 PURE 1 NOT EXIST 54.3 81.2 EXISTS EXISTS99.8 0.4 EXISTS COPPER Sn ON ALLOY OUTERMOST SURFACE TEST ITEM INITIALAFTER 160° C. × 120 hrs AFTER SPRAYING SALT WATER AFTER CORROSION BY GASHEAT CONTACT CONTACT CONTACT CONTACT FRETTING RESISTANCE TEST NO.APPEARANCE RESISTANCE APPEARANCE RESISTANCE APPEARANCE RESISTANCEAPPEARANCE RESISTANCE RESISTANCE AFTER SLIDING 1 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 2 ○○ ○ ○ ○ ○ ○ ○ ○ ○ 3 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 4 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 5 ○ ○ ○ ○○ ○ ○ ○ ○ ○ 6 ○ ○ ○ ○ ○ ○ ○ ○ Δ Δ 7 ○ ○ ○ ○ ○ ○ ○ ○ Δ Δ 8 ○ ○ ○ ○ ○ ○ ○○ Δ Δ 9 ○ ○ Δ Δ ○ ○ ○ ○ ○ Δ 10 ○ ○ Δ Δ Δ Δ Δ Δ Δ Δ 11 ○ ○ ○ ○ ○ ○ ○ ○ ○○ 12 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 13 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 14 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○15 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 16 ○ ○ ○ ○ ○ ○ ○ ○ Δ Δ 17 ○ ○ Δ Δ ○ ○ ○ ○ Δ Δ 18○ ○ Δ Δ Δ Δ Δ Δ Δ Δ 19 ○ ○ ○ ○ ○ ○ ○ ○ × ×

The followings are contents of items in Tables 3 and 4.

-   (a) Mode of Cu—Sn:    The whole Cu—Sn, partial Cu—Sn and pure Sn on the outermost surface    mean materials having laminate structures shown diagrammatically in    FIG. 14.-   (b) Analysis of Copper Concentration Point:    Copper concentration of each layer of (1) through (4) shown in FIG.    14 was measured in the same manner with what described in the first    embodiment.-   (c) Existence of Surface Pure Sn on Concentration Analysis Line:    Existence of pure Sn on the surface of the partial layer shown in    FIG. 14-   (d) Initial, after 160° C.×120 hrs:    The test of the specimen was carried out in its original state or    carried out after applying thermal load of 160° C.×120 hrs.-   (e) After Spraying Salt Water and After Gas Corrosion:    The test was carried out after spraying salt water of 5% of    concentration to the specimen or the test was carried out after    corroding 96 hours within gas at 35° C.-   (f) Appearance:    Those whose color did not change visually were indicated by “◯ and    those whose color changed were indicated by “X”.-   (g) Contact Resistance:    The contact resistance was measured in the same manner with the    before fine sliding described in the first test example. Those whose    contact resistance value is under 5 Ωm were indicated by “◯”, more    than 5 Ωm and under 10 Ωm were indicated by “Δ” and more than 10 Ωm    were indicated by “X”.-   (i) Heat Resistance after Sliding:    It is presumed that sliding load and thermal load are repeated in    the same time or alternately when an environment in which the    material is mounted in a vehicle is considered. Simulating such    phenomenon, the contact resistance of the material treated by 80° C.    of thermal load×100 hrs after sliding 200 times was measured. Those    whose contact resistance value is under 5 Ωm were indicated by “◯”,    more than 5 Ωm and under 10 Ωm were indicated by “Δ” and more than    10 Ωm were indicated by “X”.

When the outermost surface the specimen is only pure Sn as indicated inthe test No. 19 in Table 1, its fretting resistance and heat resistanceafter sliding are inferior. Meanwhile, it can be seen that if the Cuconcentration on the surface side is lower than that on the base sidelike the test Nos. 1 through 16, the fretting resistance is better thanthat of the test No. 19.

It is noted that it was confirmed that the Cu concentration graduallydecreases from the base side to the surface side in the Cu—Sn alloylayer in the test Nos. 1 through 15.

It can be also seen that in the test No. 6 through 8 whose Cuconcentration in the half of the base side is 50 to 100 mol % and whoseCu concentration in the half of the surface side is not in a range of 40to 95 mol %, their fretting resistance and heat resistance after slidingare inferior as compared to the test No. 1 through 5 that are within therange. In the same manner, when pure Sn is partially dispersed withinthe Cu—Sn alloy layer, it can be seen that even the test No. 16 whose Cuconcentration in the half of the substrate side is 50 to 100 mol % andwhose Cu concentration in the half of the surface side is low hasinferior fretting resistance and heat resistance after sliding ascompared to the test Nos. 11 through 15 that are within the range.

The test Nos. 9, 10, 17 and 18 whose Cu—Sn alloy layer is out of therange of 0.1 to 3.0 μm have inferior fretting resistance and heatresistance after sliding as compared to the test Nos. 1 through 5 and 11through 15 that are within the range. Further, when the thickness of theCu—Sn layer is thicker than 3.0 μm, they are inferior than the test Nos.1 through 15 and 11 through 15 in the test of after-thermal load of 160°C.×120 hrs as indicated by the test Nos. 9 and 17. When the thickness ofthe Cu—Sn layer is thinner than 0.1 μm, they are inferior not only inthe test after-thermal load of 160° C.×120 hrs but also in the testafter spraying salt water and after corroding by gas as indicated by thetest Nos. 10 and 18.

The test Nos. 1 through 5 and 11 through 15 that fall all within theranges described above obtained good results in all evaluation items.

Fourth Exemplary Embodiment

A plated laminate was fabricated by plating Ni, Cu and Sn on the stripof copper alloy in the same manner with the first embodiment and a heattreatment was implemented to obtain each metallic material forelectrical electronic component shown in the following Table 4. However,the thicknesses of plating of Cu and Sn are thickness indicated bythicknesses of Cu and Sn in Table 4 and no Ni plating is implemented inthe case when there is no undercoat Ni layer in Table 4.Each metallic material thus obtained was tested as specimen and Table 4shows their plating mode and evaluation results.

TABLE 4 PLATING MODE Cu—Sn LAYER POINT ANALYSIS OF Cu WHETHERCONCENTRATION (REMAINING PART: Sn PURE Sn WHETHER LAYER MANUFACTURINGCONDITION PURE Sn EXISTS {circle around (1)} EXISTS WHETHER DESIGNEDVALUE REFLOW FURNACE OR NOT ON SUR- BASE OR NOT UNDERCOAT THICK- THICK-TEMPER- PASSING COOLING TANK MODE OF SURFACE OF FACE SIDE WITHIN NiLAYER TEST NESS OF NESS OF ATURE TIME TEMPER- PASSING Cu—SnCONCENTRATION SIDE [mol UPPERMOST EXISTS NO. Sn [μm] Cu [μm] ° C. secATURE ° C. TIME sec LAYER ANALYSIS LINE [mol %] {circle around (2)}{circle around (3)} %] SURFACE OR NOT 21 0.1 0.1 650 7 40 7 WHOLE NOTEXIST 65 71.2 76.1 82.5 NOT EXIST NOT EXIST SURFACE OF Cu—Sn 22 0.250.15 650 15 35 15 PARTIAL NOT EXIST 63.1 68.1 74.5 96.5 NOT EXIST NOTEXIST Cu—Sn EXISTS 65.2 72.3 76.1 97.2 23 0.4 0.4 700 8 50 8 WHOLE NOTEXIST 52.5 61.3 72.4 83.3 NOT EXIST NOT EXIST SURFACE OF Cu—Sn 24 0.20.2 710 5 30 5 WHOLE NOT EXIST 70.5 79.3 81.1 82.2 NOT EXIST EXISTSSURFACE OF Cu—Sn 25 0.3 0.3 740 7 40 7 WHOLE NOT EXIST 71.4 80.4 81.982.8 NOT EXIST EXISTS SURFACE OF Cu—Sn 26 0.5 0.6 740 7 40 7 PARTIAL NOTEXIST 65.5 68.2 70.7 97.6 NOT EXIST EXISTS Cu—Sn EXISTS 66.4 70.1 73.597.3 27 0.8 0.9 760 12 60 12 PARTIAL NOT EXIST 46.5 57.3 68.1 71.3 NOTEXIST NOT EXIST Cu—Sn EXISTS 41.1 55.6 66.1 79.5 28 0.5 0.8 780 7 40 7PARTIAL NOT EXIST 67.1 71.1 75.2 98.1 NOT EXIST EXISTS Cu—Sn EXISTS 68.172.2 76.1 98.3 29 1.3 1.3 800 20 40 20 WHOLE NOT EXIST 42.1 48.8 55.663.5 NOT EXIST EXISTS SURFACE OF Cu—Sn 30 1.3 1.2 800 10 40 10 PARTIALNOT EXIST 51.1 62.1 74.5 96.5 NOT EXIST NOT EXIST Cu—Sn EXISTS 53.5 65.177.8 97.2 31 1.1 0.5 780 50 60 50 — — 72 78 82 84 EXISTS NOT EXIST 320.5 0.5 740 1 40 1 — — 54.1 85.2 91.1 98.1 EXISTS EXISTS 33 0.8 0.8 38010 50 10 — — 61.1 87.5 91.2 96.4 EXISTS EXISTS 34 0.7 0.6 200 5 40 5 — —51.1 82.4 93.5 99.1 EXISTS NOT EXIST 35 0.9 0.5 900 7 40 7 — — 80.5 82.482.6 83.1 EXISTS EXISTS TEST ITEM AFTER AFTER SPRAYING AFTER CORROSIONINITIAL 160° C. × 120 hrs SALT WATER BY GAS FRET- HEAT RE- CONTACTCONTACT CONTACT CONTACT TING SISTANCE TEST APPEAR- RESIS- APPEAR- RESIS-APPEAR- RESIS- APPEAR- RESIS- RESIS- AFTER NO. ANCE TANCE ANCE TANCEANCE TANCE ANCE TANCE TANCE SLIDING 21 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 22 ○ ○ ○ ○ ○○ ○ ○ ○ ○ 23 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 24 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 25 ○ ○ ○ ○ ○ ○ ○○ ○ ○ 26 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 27 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 28 ○ ○ ○ ○ ○ ○ ○ ○ ○○ 29 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 30 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 31 ○ ○ ○ ○ ○ ○ ○ ○ × ○32 ○ ○ ○ ○ ○ ○ ○ ○ × Δ 33 ○ ○ ○ ○ ○ ○ ○ ○ × × 34 ○ ○ ○ ○ ○ ○ ○ ○ × Δ 35○ ○ ○ ○ ○ ○ ○ ○ × ○

While it can be seen that the Cu concentration gradually decreases fromthe base side to the surface side in all of the tested items, the degreeof decrease of the test No, 35 whose heating temperature is as high as900° C. is small. The fretting resistance of the test Nos. 31 through 35having the pure Sn layer on the outermost surface is inferior. Stillmore, the test Nos. 32 and 34 whose heating and cooling times are shorthave inferior heat resistance after sliding.

INDUSTRIAL APPLICABILITY

The metallic material for electrical electronic component of theinvention may be readily manufactured and may be suitably used for aconnecting or sliding portion of a connector terminal.

While the invention has been described with its modes, the inventorshave no intention of limiting any detail of the explanation of theinvention unless specifically specified and consider that the inventionshould be construed widely without going against the spirit and scope ofthe invention indicated by the scope of the appended Claims.

This application claims priority from Japanese patent application Nos.2007-142469 filed on May 29, 2007 and 2008-140186 filed on May 28, 2008.The entire contents of which are incorporated herein by reference.

The invention claimed is:
 1. A metallic material for an electricalelectronic component comprising a Cu—Sn alloy layer provided on aconductive base, wherein said Cu—Sn alloy layer has a Cu concentrationgradually decreasing from a side of the conductive base toward a surfaceside thereof, said Cu—Sn alloy layer has a thickness of 0.1 to 3.0 μm,and said Cu—Sn alloy layer exists as the outermost surface of themetallic material, wherein said Cu—Sn alloy layer includes a halfportion on the side of the conductive base having the Cu concentrationof 65 to 100 mol % and the Sn concentration of 0 to 35 mol %, and a halfportion on the surface side having the Cu concentration of 65 to 85 mol% and the Sn concentration of 15 to 35 mol %.
 2. The metallic materialfor an electrical electronic component according to claim 1, whereinsaid Cu—Sn alloy layer contains Sn or a Sn alloy dispersed partially. 3.The metallic material for an electrical electronic component accordingto claim 2, further comprising one layer composed of Ni, Co, Fe, or analloy thereof provided on the conductive base, said Cu—Sn alloy layerbeing provided on the one layer.
 4. The metallic material for anelectrical electronic component according to claim 2, further comprisingtwo layers composed of Ni, Co, Fe, or an alloy thereof provided on theconductive base, said Cu—Sn alloy layer being provided on the twolayers.
 5. The metallic material for an electrical electronic componentaccording to claim 1, further comprising one layer composed of Ni, Co,Fe, or an alloy thereof provided on the conductive base, said Cu—Snalloy layer being provided on the one layer.
 6. The metallic materialfor an electrical electronic component according to claim 1, furthercomprising two layers composed of Ni, Co, Fe, or an alloy thereofprovided on the conductive base, said Cu—Sn alloy layer being providedon the two layers.
 7. The metallic material for an electrical electroniccomponent according to claim 1, wherein the Cu—Sn alloy layer has athickness of 0.3 to 1.5 μm.
 8. A method for manufacturing a metallicmaterial for an electrical electronic component, comprising the stepsof: laminating sequentially Cu and Sn on a conductive base directly orvia a layer composed Ni, Co, Fe, or an alloy thereof, to form alaminate; applying a heat treatment on the laminate; and applying acooling treatment on the laminate treated with the heat treatment,wherein the. metallic material comprises a Cu—Sn alloy layer provided onthe conductive base, said Cu—Sn alloy layer has a thickness of 0.1 to3.0 μm, said Cu—Sn alloy layer exists as the outermost surface, of themetallic material, and said Cu—Sn alloy layer has a Cu concentrationgradually decreasing from a side of the conductive base toward a surfaceside thereof, and said Cu—Sn alloy layer includes a half portion on theside of the conductive base having the Cu concentration of 65 to 100 mol% and the Sn concentration of 0 to 35 mol %, and a half portion on thesurface side having the Cu concentration of 65 to 85 mol % and the Snconcentration of 15 to 35 mol %.
 9. The method for manufacturing themetallic material for an electrical electronic component according toclaim 8, wherein, in the step of applying the heat treatment, saidlaminate passes through a reflow furnace at an in-furnace temperature ofnot lower than 300° C. and lower than 900° C. over 3 to 20 seconds. 10.The method for manufacturing the metallic material for an electricalelectronic component according to claim 9, wherein, in the step ofapplying the cooling treatment, said laminate passes through a liquid ata temperature between 20° C. and 80° C. over 1 to 100 seconds.
 11. Themethod for manufacturing the metallic material for an electricalelectronic component according to claim 9, wherein, in the step ofapplying the cooling treatment, said laminate passes through a gas at atemperature between 20° C. and 60° C. over 1 to 300 seconds, and thenthrough a liquid at a temperature between 20° C. and 80° C. over 1 to100 seconds.
 12. The method for manufacturing the metallic material foran electrical electronic component according to claim 8, wherein thestep of applying the cooling treatment forcibly ends the diffusion of Cuand Sn in the mid-course of the diffusion thereof or rapidly reduces thediffusion speed of Cu and Sn.
 13. The method for manufacturing themetallic material for an electrical electronic component according toclaim 8, wherein, in the step of applying the cooling treatment, saidlaminate passes through a liquid at a temperature between 20° C. and 80°C. over 1 to 100 seconds.
 14. The method for manufacturing the metallicmaterial for an electrical electronic component according to claim 8,wherein, in the step of applying the cooling treatment, said laminatepasses through a gas at a temperature between 20° C. and 60° C. over 1to 300 seconds, and then through a liquid at a temperature between 20°C. and 80° C. over 1 to 100 seconds.
 15. The method for manufacturingthe metallic material for an electrical electronic component accordingto claim 8, wherein the Cu and Sn layer are formed by plating.
 16. Themethod for manufacturing the metallic material for an electricalelectronic component according to claim 15, wherein the Sn layer has athickness of 0.01 to 5.0 μm.
 17. The method for manufacturing themetallic material for an electrical electronic component according toclaim 8, wherein the Sn layer is formed by electroplating.